Transmission-line connector



1964 l. s. BLONDER ETAL 3,

TRANSMISSIONLINE CONNECTOR Filed Aug. 10, 1962 INVENTORS ISAAC S.BLONDER WALTER EDWARD SAMPSON ATTORNEYS United States Patent 3,154,362TRANSMISSIGN-LENE CONNECTOR Isaac S. Blonder, West Orange, and WalterEdward Sampson, Westdeld, N.J., assignors to Blonder Tongue Electronics,Newark, N.J., a corporation of New Eersey Filed Aug. 10, 1962, Ser. No.216,188 Claims. (Cl. 339-97) The present invention relates totransmission-line connectors and, more particularly, to connectors usedwith coaxial transmission lines and the like, such as those employed inaudio-frequency and radio-frequency systems.

Several types of connectors have been evolved for attachment to the endsof transmission lines without requiring solder connections and theirattendant inconvenience and other disadvantages. One successfulconnector of this character, for example, is disclosed in United StatesLetters Patent No. 3,001,169, granted on September 19, 1961, to I. S.Blonder, one of the present applicants. Such connectors, however,generally require locking collars and other moving parts and/or heavymetal construction, including, in some instances, machined parts or thelike, that, in some applications, where very low cost and very rapidassembly are required, are not desirable.

An object of the present invention, accordingly, is to provide a new andimproved solderless connector for a coaxial transmission line or thelike that is particularly adapted for very low cost and facileattachment and that may be fabricated inexpensively from thin sheelmetal.

A further object is to provide a novel connector of more generalutility, as well.

Other objects will become evident in the description to follow and willbe particularly pointed out in the appended claims.

In summary, the objects of the present invention are attained with theaid of a hollow male plug for receiving the inner conductor of the line,the plug being partially peripherally closed near its free end toprovide a reduced diameter terminal portion, and a rubber-like insertextending longitudinally Within the hollow of the plug and through andbeyond the reduced-diameter terminal portion and free end thereof, saidinsert being of cross-dimension slightly less than the innercross-dimension of the plug in order to prevent compression thereofwithin the hollow of the plug, but of slightly greater cross-dimensionthan the reduced-diameter terminal portion in order to compress theinsert at that terminal portion.

The invention will now be discussed in connection with the accompanyingdrawing in which,

FIG. 1 is a perspective of a connector embodying the invention inpreferred form;

FIG. 2 is a section view taken upon the line 22 of FIG. 1, looking inthe direction of the arrows, but upon a greatly enlarged scale; and

FIG. 3 is a longitudinal section of the connector of FIG. 1, also uponan enlarged scale, showing a coaxial transmission line secured thereto.

Referring to the drawing, the connector is provided with a substantiallycircular-cylindrical male conductive plug 1 for receiving the innerconductor 7, FIG. 3, of a coaxial transmision line, 19, the outerconductor 3 of which is insulated from the inner conductor 7 at 3' andis itself covered with insulation at 3". The plug 1 is partiallyperipherally closed near its free end, as at 1', to provide a reduceddiameter terminal portion for a purpose later explained.

A resilient insert 6, as of, for example, rubber, neoprene and the like,is disposed to extend longitudinally within the hollow of the plug 1 andthrough and beyond the reduced-diameter terminal portion 1 and free endthereof. As is later evident, the length of the insert 6 is preferably"ice greater than that of the plug 1. The insert 6 is also preferably ofsubstantially square cross-section and of diagonal cross-dimension justslightly larger than the inner crossdimension of the plug, as moreparticularly shown in FIG. 2. The side-dimensions of the insert areaccordingly less than the inner diameter of the plug, in order toprevent substantial compression of the insert within the hollow of theplug when an inner conductor 7, of diameter substantially of therelative dimension shown in FIG. 3, is inserted into the plug in thespace 12, FIG. 2, between a side of the insert 6 and the adjacent innerwall portion of the plug 1. The diameter of the inner conductor 7 isthus not substantially greater than the maximum crossdimension of thespace 12 in the preferred construction. Such a goemetry and actualdimensioning insures that the frictional force exerted upon the cornersof the substan- 'ally square resilient insert 6 by the inner wall of theplug 1, holds the insert 6 against longitudinal movement as the innerconductor 7 is inserted into the plug 1. In the absence of suchrelationship, the resilient insert 6 has been found to be forcedlongitudinally along the plug 1 and out of the reduced-diameter terminalposition 1' as the inner conductor 7 is so inserted.

The insert 6, however, is made of greater cross-dimension than thereduced-diameter terminal portion 1 of the plug 1 in order to compressthe resilient insert 6 at that terminal portion and to permit anexpansion therebeyond, as at 6', FIG. 3. Though the inner conductor 7 isforced into contact with the inner surface of the plug 1 substantiallythroughout the length thereof, it has been found that an invariablyreliable electrical connection is established and maintained at theregion 7' of forced engagement against the reduced-diameter terminalfront wall 1.

The plug 1, moreover, is coaxially mounted with respect to an outercylindrical conductive shell 2, being carried by an apertured insulatingdisc 4, crimped as at 2' to an end of the shell 2.

The conductive shell 2 itself is longitudinally slotted to provide aplurality of resilient fingers 18 extending rearwardly over asubstantial portion of the length thereof, between longer fingers orcylindrical wall strips 19. The fingers or strips 19, are provided withinwardly extending prongs 19 for piercing the outer coaxial lineinsulation 3" of the line 11 inserted there-within. Electricalconnection is thus established with the outer conductor 3 of the lineit; as the prongs 19' are forced radially inward by a clamping ring 21,fitted over the resilient inwardly bent terminal portions 19" at thefree ends of the strips 19.

As before stated, this construction enables ready and inexpensivefabrication from sheet metal, and obviates the means for heavy parts,locking collars and similar devices, while providing a strong andreliable solderless connection to the line.

Modifications will occur to those skilled in the art, and all such areconsidered to fall within the spirit and scope of the invention asdefined in the appended claims.

What is claimed is:

1. Apparatus for providing a facile connection to a transmission line,comprising a tubular conductive plug having an opening at its forwardend and an opening at its rearward end with a passage extending betweensaid openings, said plug having an interior peripheral constrictionadjacent to the opening at its forward end to provide a terminal portionof reduced cross-dimension, a resilient insert extending longitudinallywithin said passage and through said terminal portion, said inserthaving a crossdimension less than the corresponding cross-dimension ofsaid passage to provide a space between said insert and said plug, saidinsert being free of substantial compression in said passage, saidcross-dimension of said insert being a greater than the correspondingcross-dimension of said terminal portion and said insert beingsubstantially resiliently compressed by said terminal portion, atransmission line conductor being introduced into said rearward end ofsaid plug and passing longitudinally through said space between saidinsert and said plug, and between said terminal portion and theresiliently compressed insert thereat, said conductor being forced intoreliable electrical connection with said terminal portion by saidinsert.

2. The invention of claim 1, said insert being substantially rectangularin cross-section, having its corners engaging the interior surface ofsaid plug, and having its sides spaced from said surface.

3. The invention of claim 2, said plug being a metal sleeve of circularcross-section, said insert being of rubberlike material and having asquare cross-section with diagonal dimensions slightly greater than theinner diameter of said sleeve.

4. A connector for a coaxial transmission line comprising a tubularconductive plug having an opening at its forward end and an opening atits rearward end with a passage extending between said openings, saidplug having an interior peripheral constriction adjacent to the openingat its forward end to provide a terminal portion of reducedcross-dimension, a resilient insert extending longitudinally Within saidpassage and through said terminal portion, said insert having across-dimension less than the corresponding cross-dimension of saidpassage to provide a space between said insert and said plug, saidinsert being free of substantial compression'in said passage, saidcross-dimension of said insert being greater than the correspondingcross-dimension of said terminal portion and said insert beingsubstantially resiliently compressed by said terminal portion, aconductive shell having a forward end secured to the rearward end ofsaid plug by an insulating washer, said shell having a plurality ofrearwardly extending resilient fingers at least one of which is providedwith inwardly extending prong means, said shell being dimensioned toreceive the end of a coaxial line'and having means for clamping thefingers to cause said prong means to engage the outer conductor of theline, said plug being dimensioned to receive the inner conductor of theline through the opening at the rearward end of the plug, through thespace between said insert and said plug, and between said terminalportion and the resiliently compressed insert thereat, to cause saidinner conductor to be forced into reliable electrical connection withsaid terminal portion by said insert.

5. The connector of claim 4, the length of said insert being greaterthan the length of said plug.

References Cited in the file of this patent UNITED STATES PATENTS2,630,468 Felts et al Mar. 3, 1953 2,677,118 Stone Apr. 27, 19542,807,791 Wallo Sept. 24, 1957 2,820,209 Whitted Jan. 14, 1958 2,839,595Felts et al June 17, 1958 3,001,169 Blonder Sept. 19,1961 3,024,437 VanDeusen Mar. 6, 1962 3,059,208 Concelman H Oct. 16, 1962 FOREIGN PATENTS531,947 Great Britain Jan. 14, 1941

1. APPARATUS FOR PROVIDING A FACILE CONNECTION TO A TRANSMISSION LINE,COMPRISING A TUBULAR CONDUCTIVE PLUG HAVING AN OPENING AT ITS FORWARDEND AND AN OPENING AT ITS REARWARD END WITH A PASSAGE EXTENDING BETWEENSAID OPENINGS, SAID PLUG HAVING AN INTERIOR PERIPHERAL CONSTRICTIONADJACENT TO THE OPENING AT ITS FORWARD END TO PROVIDE A TERMINAL PORTIONOF REDUCED CROSS-DIMENSION, A RESILIENT INSERT EXTENDING LONGITUDINALLYWITHIN SAID PASSAGE AND THROUGH SAID TERMINAL PORTION, SAID INSERTHAVING A CROSSDIMENSION LESS THAN THE CORRESPONDING CROSS-DIMENSION OFSAID PASSAGE TO PROVIDE A SPACE BETWEEN SAID INSERT AND SAID PLUG, SAIDINSERT BEING FREE OF SUBSTANTIAL COMPRESSION